A ROM is used to store the table for multiplication of two 8-bit unsigned…
1996
A ROM is used to store the table for multiplication of two 8-bit unsigned integers. The size of ROM required is
- A.
256 × 16
- B.
64K × 8
- C.
4K × 16
- D.
64K × 16
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Correct answer: D
A ROM lookup table receives the two operands as address inputs.
Each operand is 8 bits, so the two operands together require 8 + 8 = 16 address bits. Therefore, the number of ROM locations required is:
2¹⁶ = 65536 = 64K locations.
The product of two 8-bit unsigned integers can be as large as:
255 × 255 = 65025.
This value requires 16 bits, since the product of two 8-bit numbers can be up to 16 bits wide.
Therefore, the ROM must have 64K locations, each storing a 16-bit product. Hence, the required ROM size is 64K × 16.